Human wounds heal at a rate nearly three times slower than those of other primates, with researchers attributing this to our lack of fur and the unique community of bacteria that inhabit our skin.
The Slow Healing of Human Wounds: A Unique Adaptation
Human wounds take almost three times as long to heal as those of other primates, which may come down to our lack of fur. This unique characteristic is a result of an evolutionary adaptation that has been shaped by the loss of body hair.
The Evolutionary Context
Our skin is host to a thriving community of bacteria, some of which help to restore and protect our epidermis. However, this also means that we are more prone to infection. In contrast, other primates have fur that provides natural protection against the elements and reduces the risk of infection.
The Science Behind Slow Healing
A study published in the Proceedings of the Royal Society B: Biological Sciences found that human wounds heal at a rate of 0.61 millimetres per day, compared to 0.25 millimetres per day for patients with skin tumours removed. This suggests that there may be an evolutionarily optimal healing rate for most mammals, but not humans.
Wound healing is a complex, multi-stage process involving inflammation, proliferation, and remodeling.
It begins with hemostasis, where platelets form a blood clot to stop bleeding.
Inflammation follows, with white blood cells arriving to fight infection.
Proliferation involves the growth of new tissue, including 'collagen production'.
Remodeling occurs last, where the wound is strengthened by further collagen deposition and tissue reorganization.
The Role of Body Hair
Researchers believe that the slower wound-healing rate in humans may be linked to evolutionary changes, such as the reduction in body hair. A higher hair density leads to an increase in stem cell numbers, which results in faster healing. This theory is supported by the fact that chimpanzees, our closest living relatives, have a similar wound-healing rate to other non-human primates.
Compensating for Slow Healing
Social support, in the form of food sharing, nursing and medicine, may have compensated for the disadvantages of slow healing. Despite this, human wounds remain slower to heal than those of other animals.
- newscientist.com | Our wounds heal slower than the cuts and scrapes of other primates
